Poured concrete may be influenced by drying, sudden changes in temperature, or the like during curing, which causes insufficient hydration reaction. When this happens characteristics such as the strength, durability, and appearance of the concrete may be decreased below design values. Therefore, in the curing of concrete, conditions such as the moisture amount, the temperature, and the like of the poured concrete surface are preserved within desired ranges for a desired time.
Such concrete curing methods include methods for reducing the evaporation of moisture from the poured concrete surface, for example, sealed curing and coating curing; methods including supplying water to the poured concrete surface, for example, spray curing and flooding curing; methods including holding a sheet with water absorbing properties facing (in contact with) the poured concrete surface, for example, compression curing; and methods including supplying moisture between the sheet and the concrete surface while holding the sheet facing (in contact with, or close proximity to) the poured concrete surface, for example, water supply curing. These methods are not always clearly distinguishable.
Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2002-81210A) describes “A concrete curing sheet laid on a concrete surface, in which an amount of moisture lost by the concrete surface is replenished, and the concrete is preserved in a wet state and cured. The concrete curing sheet is provided with a base material sheet, and a plurality of protrusions secured on the side laid on the concrete surface of the base material sheet with spaces being formed between each of the protrusions, each of the protrusions having a width of 2 to 20 mm, each of the protrusions being arrayed two dimensionally, and each of the protrusions being formed from a wet material which swells upon absorbing water. When the concrete curing sheet is laid on the concrete surface, each protrusion swells as a result of absorbing water, the side surfaces of each protrusion bulge into each of the spaces, each space is narrowed, the concrete curing sheet holds a flat shape, the surfaces of each protrusion contact the concrete surface, and each protrusion replenishes the moisture on the concrete surface.”
Patent Document 2 (Japanese Unexamined Patent Application Publication No. H10-46816A) describes “A method for curing a poured formed concrete body, in which, after removing a framework for forming the concrete body, a curing sheet, which is provided with a fiber material and a porous drain tube embedded in the fiber material, is installed to cover the surface of the concrete body such that the fiber material contacts the surface of the concrete body and the porous drain tube is substantially horizontal, and water is supplied through the porous drain tube”.